Chalk up Paul O’Neill as one right fielder whose conversion to first base never took.

In fact, after playing 21 games at first for Cincinnati in 1988, O’Neill wanted to retreat to the safety of the outfield grass “as quick as possible.” “Even during batting practice, I couldn’t wait to get to the outfield,” the former Yankees fan favorite told the Post on the eve of the Division Series opener.

“It wasn’t me. I wasn’t a true infielder.” The Yankees are attempting a similar shoehorning of Gary Sheffield this postseason, although O’Neill thought it would go better than his own aborted conversion. Still, he was crossing his fingers that it wouldn’t blow up in the Bombers’ faces.

“It’s a little different situation, because I was an outfielder who had never been an infielder,” O’Neill said hours before first pitch. “Gary’s been an infielder.

“But still, there’s times in the game when you have a play and you have to think about it and it’s not a reaction. Then it can be tough.

“You just hope it doesn’t come down to something like that.” Prior to this season, Sheffield had started 562 career games in the infield, 94 at short and 468 at third. O’Neill, who only played three career games at first after the failed experiment in ’88, said fielding ground balls and catching throws from infielders should be no problem.

“It’s a freak play, a throw to third or a throw to second or a bunt play that you’re not accustomed to doing that weird things can happen,” O’Neill said.

“But you know, Joe Torre usually has good feelings about these things.

“From what I understand, he’s very comfortable with [Sheffield] at first.” After starting only nine games at the position during the regular season, Sheffield’s final exam began last night in Game 1 against Detroit. He admitted the position was more difficult than he originally thought, and initially called himself “a fish out of water.” If you’re looking for potentially foreboding news, he admitted on Monday that he hadn’t worked on bunt defense since the last road trip in Toronto.

“I’m getting comfortable, but the thing is, I just have to be conscious of it,” Sheffield said during the workout day. “When you don’t have a lot of experience, things don’t always don’t come naturally in life.

“For the most part, I’ve passed some of the tests and failed at some things. But the things I’ve failed at, I’m trying to correct.”